Valve setting calculator



Sept- 24, 1940- J. c. HOLDMAN VALVE SETTING' CALCULATOR Filed NOV. 25, 1958 Patented Sept. 24, 1940 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to valve setting calculators, and particularly to calculating devices for aid in synchronizing or equalizing the slide valve mechanism of steam engines, and is utilized to great advantage in servicing the valves and valve gear of steam locomotives.

It has heretofore been necessary at intervals, usually incident to the routine servicing of steam locomotives, to check, and usually to 1* readjust the position of each of the steam valves as to its timed or operative relation to the piston of the corresponding cylinder. Usually the adjustments include, to insure optimum valve positioning, two more or less separate, and yet related n changes in the valve operating mechanism. The first of these consists in effecting any necessary change in the spacing, say of a piston type valve, and the valve crosshead by which it is operated; otherwise expressed in the manner usually employed, this change involves a variation in absolute length oi the valve stem or valve-operating rod by or through which the valve is connected to its crosshead. The second adjustment is cared for in usual practice with steam locomotives, by changing, if and as necessary, the length of the eccentric rod which serves as one of the connecting elements between the reverse and cutoff link, and the valve actuating crank or eccentric. The procedure heretofore resorted to is well known to the skilled railroad mechanic and need not be herein described in detail. It is suicient for the present to note that because of the plurality of careful measurements involved, and ensuing arithmetical calculations, the process is usually time-consuming and fraught with possibility of error.

The present invention has as its principal object, an improved device by which certain values, easily arrived at by measurement, may be set up on the device which is in the nature of a calculator of slide rule type, and which is further so designed as to enable deriving by direct reading, any change necessary to be made in the 45 length of valve stem, and also so designed that the device provides, when fully set up, a value which, through an easy conversion factor, will give with certainty any necessary change in length of the eccentric rod. From this fact and the following more detailed description it will appear that the valve setting device of the present invention obviates all of the protracted arithmetical processes heretofore required incident to the synchronization of steam locomotive valves, for

(Cl. 23S-70) example, with the sole exception of a single simple multiplying operation hereinafter explained.

Yet another object of the invention is attained in a simple, compact, easily readable, low-cost calculating device for the purpose noted. 5

Yet another object of the invention is attained in a valve-setting calculator particularly adapted for the purpose noted, and which is so designed, and provided with indicia such that the device in use bears a definite, physical fore-and-aft relation to the locomotive or other steam engine of slide valve type, such as positively to indicate to the user whether the reading indicating a change in the valve mechanism is either an increment or decrement, and further such that there is obviated`any confusion between the results obtained with respect to the two valve gears on opposite sides of the locomotives.

rihe foregoing and numerous other objects and advantages will hereinafter appear from the following description of a presently preferred enibodiment of the invention, considered in connection with the accompanying drawing, in which:

Fig. l is a plan or top elevation of a calculating device for the setting of stem engine valves, and constructed in accordance with the present invention; Fig. 2 is a transverse section through the device of Fig. l, as viewed along line 2-2 thereof; Fig. 3 is a schematic or diagrammatic view of a simplified form of valve linkage to illustrate the manner of usage of the device of the present invention, and Fig. 4 is an enlarged fragmentary side elevation of a valve stem to which port and travel marks have been applied, incident to the usage of the calculator to be described.

Referring now by characters of reference to the drawing, and rst to the structure of a calculating device through which the desired results are accomplished, it is preferred to utilize a base or frame of formed sheet metal, indicated generally at I0, as a guiding holder for the several slide elements. The channeled base I Il is formed, as best appears in the section of Fig. 2, with a planar bottom portion and upstanding margins I I, the latter being turned inwardly to form guiding anges or lips I2, the portions II and I2 being similar on the top and bottom margins of the base except of course that the portions I2 are 50 oppositely inturned. Disposed along the central median portion of the base structure is a Second iixed channel element indicated generally at I3, and having a planar bottom I4 secured as by welding or riveting to the base of the structure I0. 55

on its opposite sides, for a purpose aring. It results from the upper part of element lil at of channel form, charmar ns it and inturned latter serve guidingly to lement 25. as the portions iii, I4 and of structure are, for econr, preferably formed of sheet say of stainless sheet steel o1' other corro- -esisting It is however to be tcod that the invention is not restricted embodiment to the use of any particular metal or even to the use of the die-formed sheet metal shown and for convenience hereinafter "cierren to in description. Obviously some or all ci these elements may be formed of suitable grades of wood, composition, plastics, or the like.

As will best appear from Fig. 2, the intermediate e structure ifi serves with the upstanding o, portions l i and flanges l2, to forni guide grooves f -fr convenience, -nay be described as lying above and below the central slide One such as consisting oi top and 'stm orb

par

arrangement or slides below the central nd the guide structure i3, ill, i6 for the substantially the saine along the lower of the calculator as that heretofore described in the upper portieri. A slide includes spaced parallel top and bottom eiernents similar spending parts of slide Ei; extended ions and 23 correspond respectively cse indicated 22 and on slide 2l, so .ie guiding extensions and 33 operate in the gro ves constituted by parts l l and in the graue seat or channel i5. posed between the spaced parallel top and i portions of slide 2S, is a companion or ting sli le element it being understood the slide cooperates with the slide 2G, i being movable independently thereof, me manner that slide is carried by and es with the slide El. It is understood of that the ends of the channels in the base and in the member S3, iii, are open, it the extension or" any of the various endwise beyond the base or frame essential to the particular purpose and of the calculator selected for present illusn of the invention, reference is now made the several indicia provided on the base and 1 as 'well as the indicator elements cooperating u ieiewith. It may rst be noted (Fig. l) that the uppermost dan-ge i2 of the base is provided leit hand end (Fig. l) with the legend "kunt of engineleft side, and near its right hand end (Fig. i) with a corresponding legend front or engineright side. These indicia are employed to enable placement of the calculator in the indicated relation to a steam engine or locomotive with which it is employed for the purposes of synchronizing the valves, in a manner more clearly hereinafter appearing.

is further to be noted that the fianges I2, both at the top and bottom marginal portions of the calculator, are each provided substantially centrally or" the base, with a score mark or base mail; identified with the legend port, these being port reference marks utilized in setting up ce in readings on the device as will clearly appear from an exemplary or illustrative usage thereof hereinafter included. More accurately expressed, these reference marks indicate a` midpoint of valve travel between beginning-portcpening positions.

Referring now to the scheme of graduation of the several slides, it will appear from Fig. l that the graduations on each of the ve slides 2i, E5,

2li and are arithmetic in nature, in distinction from the logarithmic graduations often employed on slide rules of other types utilized for general calculation. It is iurther noted from Fig. i. that the spacing of the unit markings of the slides 2i, 2t and 3Q are uniform on each slide. The exact value of this spacing is immate Lal, so long as the spacing is the same on all four ci" the last noted slide elements. The readings, as hereinar" ter will appear, are set up on the several slides of the calculator and the results taten therefrom, according to prevailing Americ..n practice, in sixty-fourths of an inch, although it is not necessary that the spacing of the units on the four slides last named, actually be of this small value.

t a great preference that the graduations on the central slide 28 be such that the units are spaced at twice the Value of the corresponding markings on the remaining four slides of the calculator; Vfor example, if the spacing of the Scoro marks on slides 2i, 2G and S0 be onethirty-second of an inch, the spacing of the unit markings on slide is one-sixteenth of an inch, the exact values against being noted as arbitrary.

Considering further the companion or cooperto the operator when in use, while the secr marks and numbering forming the scale on E are disposed to read from right to left. relation prevails with respect to slide and ii, the former being graduated om left to right, and the latter correspondingly raduated but reading from right to left. The entral slide element 23 differs from any of the our slides last described in that it is graduated from a central zero mark designated as CT (Fig. l) indicating to the user a point of center of travel of the valve, slide being graduated symmetrically from left to right, to the right of the CT mark, and in an opposite direction, Viz., from right to left, on that portion lying to the left of the CT mark.

Further describing the base marks and reference indicia as preferably utilized on the calculator, there is noted near the right hand upper margin of the frame or base lil and secured thereto, a hired pointer or indicator overlying the ruled margin or slide 2 l, this indicator being designated at It is with respect to this indicator that slide 2| is set up, as will later appear. It will be seen that a substantial economy in dimensions is attained by reason of the nested relation of slides 25 and 2 i, so that one slide lies partly within the other and is carried thereby, the same relation prevailing between slides 26 `and 3l). Slide 2| is provided with an extension 36 at its left hand end and upper margin, which extension terminates in a pointer or reference element 31, with respect to which the slide 25 is set up, when the desired value (hereinafter described) is applied thereto. The slide 25 is also provided with a depending pointer or reference element 40 which overlies and forms a base or reference marker with which cooperate the graduations or score marks on slide 20.

The structure of the companion slide elements 30 and 2G corresponds to that of slides 25 and 2| respectively, except that, of course, the latter pair of slides are relatively reversely formed and their indicia relatively inverted for ease in reading. Similar to pointer or reference element 35 there is provided, projecting upwardly from the lower margin l2 of the base frame, a pointer 4| with reference to which the slide 26 is set, Likewise, slide 26 is provided with a terminal projection 42 at its left hand lower margin, this projection terminating in a pointer 43. The inner slide 30 of this pair, is set up with respect to pointer 43, and is provided with a pointer or reference element 44, corresponding in purpose and position on the slide, to pointer 40 on element 25.

Proceeding now to a description of a typical mode of usage of the calculator for the purpose of synchronizing or equalizing the valve setting on a steam railway locomotive, there is shown by Figs. 3 and 4 a schematic representation, including only the portions necessary for present purposes, of a modied and simplied type of Walschaert valve gear; it being understood of course that the principles underlying the device may be applied to other types of valve gear on steam locomotives, as well as to the relatively more simple types of slide valve gear on stationary engines. It will be apparent to those skilled in the art, from the following description, how the calculator is employed in connection with other and prevailing types of gear.

Referring to Fig. 3, there is indicated by the numeral 45, a steam cylinder in which reciprocates a piston 46 which may be of any usual or suitable type, and to which is operatively connected the piston rod 41, operatively related to the usual crosshead (not shown), and therethrough to the rods and drivers (not shown). Port passages 48 and 49 serve to connect the cylinder 45 respectively with ports 50 and 5| of the valve chest 52, in which is reciprocally disposed a piston type slidevalve 53 of inside-admission type, provided with heads 54 and 55, the valve structure being connected to the valve stem or rod 53, and the latter being in turn connected to the valve crosshead 5|. The crosshead is pivotally Connected to and actuated by the radius bar 62, which has its outer end portion pivotally connected as at 63, to a slide 54 operating in an arcuate slot G5 of link 66. The free end portion of radius bar 62 is provided with a control rod 10 which leads to the reverse and cutoff control accessible tothe engineer.

In accordance with known practice the link 66 is provided with a fixed pivot structure 1|, about which the link is arranged to reciprocate under the im'iuence of the valve-actuating crank or eccentric, this motion being imparted to the link through the eccentric rod 12, pivotally connected as at 13 to the link 66, and pivotally connected at its opposite end as at 14, to the crank (or eccentric) 15, driven by rotary shaft 16 in well known manner. The valve gear thus described is diagrammatic in nature, and is described in present form for brevity of description of the method of usage of the calculator, as will hereinafter appear.

The structure shown, by Fig. 4 consists solely of an enlarged fragmentary portion of the valve stem 60, being a portion exterior to the valve chest and so accessible for the purpose of inscribing port marks incident to the operation of valve setting or timing by the use of the cal culator.

Proceeding now to the preferred method of correcting or synchronizing the timed setting of each of the valves such as 53, it ls presumed that the method of exact synchronization, using the calculator of the present invention, will in nearly all cases be practiced with an engine .which has been in recent service, and the condition of which is such that each valve assembly is at substantially correct leads; hence the condition is such that the object is attained in a final accurate valve setting or synchronization. If however for any reason the valve gear is entirely out of correct setting it is necessary, in accordance with known and prevailing practice, to approximate a condition of equal leads prior to the synchronization of the valve gear involving a determination of correctness of valve stem length and eccentric rod length.

Assuming that the valve setting is a matter of equalizing valve operation in forward and reverse directions of operation, one routine of synchronization to which the calculator is adapted will generally be conducted as follows: With the eccentric rod of Fig. 3 disconnected, the piston type valve 53 is manually moved to a position so that one of the steam edges of the valve is in registry with the edge of the adjacent steam port, and so that this edge is just beginning to admit steam to the corresponding end of the cylinders. A scratch or score mark is then made on the upper portion of the valve stem 60, as by the use of trarnmels. This operation is conducted with respect to both of the heads of the valve and both ports, as a result of which there are obtained the two port marks on the upper half of the valve stem as indicated by Fig. 4, these score marks indicating the valve positions in which the steam edges of the valve, respectively, are just beginning to uncover the steam ports. The following step is to connect the eccentric rod and valve gear in operative relation; the locomotive is then pulled for a sufiicient distance to operate the valve gear through a complete cycle of valve operation, the limits of the valve travel being indicated by additional punch or score marks, designated as travel marks, it being a preference and suggestion for uniformity in practice that the port marks and travel marks thus far derived, say in respect to the forward motion of the locomotive, be disposed above the center line of the valve stem. The movable radius bar 62 of Fig. 3 for example, is then shifted to a position on the opposite side of the xed link pivot 1| and located the same distance from such pivot as before, but the radius bar being now positioned so that the valve gear is in reverse setting. With the parts thus positioned, the locomotive is again pulled for a distance, or otherwise actuated again to operate the valve through a complete cycle, and score marks representing port opening po sitions and the limits of valve travel are now scored on the stem, but below the center line thereof. At this stage, the markings on the stem will appear somewhat in the manner represented by Fig. Il, wherein the two outside score marks indicated at 8S and Si, define the limits or valve travel, and the two inside marks 8G and 8l respectively indicate the limits between the beginopening movements of the valve head, corresponding to forward engine operation; the corward engine operation located thereabove.

From t e spacing of the port and travel marks and S3 as :ley appear in Fig. 4 for readily be derived four values inrespectively as dimension A between marks Sil, dimension B between marks 8l, dimension C between marks 82, and dimension D between marks S3. It is a preference, as being in g with the heretofore prevailing practice to a cal-ctlated determination for purvalues having been thus determined, they may new be set up on, or applied to the upper and lowei pairs ci coirpanion slide elements of the calculator.

Dimension A is applied to slide 25 by moving this slide to such position that the reading A in sixtyaiourths, is brought directly under or in register with pointer 3l', while dimension B is similarly set up on slide element 2 by bringing the value of B in sixty-fourths, under pointer 35. It will be seen from the fact of identical digit spacings on slides 2l and that in case there is any difference in dimensions A and B, this diierenc will result in a movement of pointer 1W on slide 25 to the right or to the left of the port mark lines located centrally of the base of the calculator.

Dimensions C and D are applied in much the same manner, respectively, to slides 3l] and 26, dimension C being applied to slide 3) by shifting this elemeirL so as to bring the reading thereon correspo to dimension C, opposite to or in register v i the pointer and moving slide 25 (with slide St) so as to bring the value D thereon under the pointer i. Similarly to slides 2l and E5, if the values oi C and D are the same, the vpointer on slide will remain in line with the port marks centrally of the calculator. Unless the valve is perfectly synchronized, the result will be that the pointer @il on slide 3G is moved to the right or the left (Fig. l) of the port marks on the flanges l2 of the base or frame of the calculator. For purposes of illustration, the result may, for example, be of the order depicted by the arrangement of parts in Fig. 1, wherein pointers lil (lli are displaced on opposite sides of the port line or lines or" the calculator, although in very many instances these pointers may be brought on the same side of the port marks, either to 'isht or left thereof. It will have appeared from the foregoing description as a preference to set up the port mark dimensions obtained by valve movement corresponding to the forward engine operation, on the upper pair of cooperating slide elements 2l and 25, and corresponding values attained for valve operation in a reverse direction, on the lower cooperating pair of slide elements 25 and 3G.

Following the settings above described, the center slide 2B is new shifted in such manner that its zero or center point indicated by the legend CT, is located midway between the pointers 4B and 44, and with the slide 2Q so adjusted, the horizontal distance from the line CT of slide 29, to the line of the port marks on flanges i2, provides a direct reading in sixty-fourths of an inch to indicate the necessary change to be made in length of the valve stein. This change in length may be eiected either by adjustment, where provided, between the valve head 53 and stem 50, or by lengthening or shortening the stem B.

It is to be noted that in using the calculator, the operator either actually or supposedly locates the calculator with respect to the engine in such manner that the operator is facing the side of the engine to be affected by the calculation or determination; i. e., in synchronizing the valve gear on the left of the engine the calculator is located with its left hand end positioned, actually or supposedly, toward the iront of the engine, while it is oppositely positioned on the opposite or right side of the engine, incident to correction oi valve setting on that side. To assist in the correct position of the calculator with respect to the engine, there are provided the two legends at the ends of the upper ilange i2 oi the base oi the calculator, heretofore referred to. With the calculator thus positioned for left side oi engine, in accordance with the legends at the end margins thereof, it is noted that in case the CT point on slide 2S lies to the left of the port marks, the adjustment needed is a shortening, or decrement in total length ol valve stem and valve. The opposite is true in case the CT point lies to the right of the port lines or marks. The converse is true with respect to the right side oi the engine.

There thus exists a denite physical relation between placement of the calculator and engine. in indicating whether the readings are to be applied positively or negatively to the parts affected. The legend on the lower rig--t hand part of the base ange (Fig. 1) is provided by way of suitable direction as to valve stein error.

There remains, incident to lull synchronization, a determination of any necessary change in rela tion of the eccentric or crank iii to the valve proper, as aiected by length of eccentric rod l2. With the calculator set up as heretofore described, the change in eccentric rod length is arrived at by determining, by direct reading, the horizontal distance from the center or CT line of slide Zl, to the pointer Llil on slide 25. This reading provides a Value which, when multiplied by a .factor to be described, gives a result expressed, say in sixty-fourths of an inch, indicating the change to be made for example, in absolute length of the eccentric rod l2. This factor arises from the inherent motion-multiplying effect of the long and short arms of the levers either on the same r opposite sides of the xed link-pivot l5. This factor represents the ratio or dimension E to dimension F (Fig. 3), so that for example, if this ratio be 3:1, the last described reading on slide 2S would require to be multiplied by thre and if this reading be, for example, two sixty-fourths, would require a change in length of the eccentric rod of six sixty-fourths inch in order correctly to equalize or compensate. Whether the value just arrived at is to be applied as an increase or as a decrease in eccentric rod length, is determined in the general manner outlined in respect to valve stern changes; for example, il the line CT falls to the right ol pointer 49 on the left side of the engine, there is indicated a decrease or decrement in length of this rod, and an increase in length in case the line CT falls to the left of pointer 4D incident to a check or test of the valve gear on the left side of the engine. It will thus appear that there exists a definite physical relation resulting from the actual or hypothetical placement of the calculator with respect to the locomotive or other engine, in accordance with the directions provided by the legends on the upper end and marginal portions of the calculator. The legend at the lower left hand margin of the base iianges, viz., Position of C. F. M. from C. T. indicates E. X. error, refers to the position of the C. T. legend with respect to pointer 40 of the present drawing, and thus refers to the nature of alteration in eccentric rod length, as above discussed. It may be noted for completeness that the legend C. F. M., last referred to, denotes center of forward motion, i. e., center of valve travel when operating in forward setting of the engine, this center being indicated by the position of pointer 4!) when the calculator is set up. Similarly, the position of pointer 44, when the calculator is set up, indicates a C. R. M. or center of reverse motion. Since the CT mark on slide il@ may be regarded as a physical division point, it is apparent that an adjustment of the eccentric rod length such as would bring the C. F. M. to the C. T. point, will serve to equalize the forward and reverse valve motions.

The foregoing has constituted for brevity, only a description of one preferred manner of usage of the calculating device, but it will be apparent therefrom that the same principles of usage prevail with respect to other known types of locomotive valve gear, as well as the slide valve mechanism of other steam engines. It is further to be noted that, although the device has been disclosed as containing slide elements of linear form, movable linearly along the base or holder, the same principles are applicable to slide rules of so-called circular or disc type, or other types utilizing any reasonable range of equivalents within the scope of the claimsr hereunto appended.

I claim as my invention:

1. In a calculating device of slide rule type for use in steam-locomotive slide valve setting, a base or holder provided with reference indicia including port reference markings, a pair of coacting, relatively slidable elements arranged for movement selectively as a unit, and individually with respect to each other, said elements bearing arithmetical graduations arranged in relatively reverse order on the elements whereby the elements are adapted to be set up to indicate a mean algebraic increment corresponding to the optimum change in relation of valve to valve operating elements, and separate indicia means carried by the base or holder for establishing different physical relations of the device to the locomotive, such as to establish the positive or negative nature of said algebraic increment respectively for the opposite cylinders of the locomotive.

2. In a calculating device for use in physical combination with a valve gear for setting the slide valves of reversible steam engines, a frame or holder, a pair of reversely graduated scalebearing elements movable on the frame, a pointer on the frame, a pointer on one of the graduated elements; a second pair of reversely graduated scale-bearing elements movable with respect to the frame and the aforesaid pair of elements, another element movable on the frame and coacting with said pairs of elements to provide a reading indicative of optimum change in valve setting, with respect to the valve operating mechanism, the last named movable element being graduated or scaled to provide readings in opposite directions from an intermediate center point thereon, the several graduated elements being arithmetically scaled, and the frame or holder carrying indicator means coacting with the engine valve gear for establishing as positive or negative, the values derived from the readings of the graduated elements.

3. In a calculating device for use as an engine accessory in setting the slide valves of reversible steam engines, a holder, a pair of reversely-graduated scale-bearing elements movable on the holder, a second pair of reversely-graduated scale-bearing elements movable with respect to the holder and the iirst said pair of elements, pointers on the holder, pointers on the paired graduated elements, and another element movable on the holder and coacting with said pairs of elements to provide a reading indicative of optimum change in setting of a valve with respect to the valve operating mechanism, the last named movable element being graduated or scaled to provide readings in opposite directions from an intermediate center point thereon, the units of graduation on said last named movable element being characterized by a spacing substantially twice that of the units of graduation on the several said paired scale-bearing elements and indicia means on the holder, arranged to establish a physical relation between the device and the engine valve gear such as to impart an algebraic significance to the values derived from the readings on the device.

4. In a calculating device for use as an engine accessory or attachment in steam-engine slidevalve setting, a base or holder, a graduated scale structure carried by and movable over the holder, the graduations on the scale structure being arithmetically spaced, a second graduated scale structures may be brought into positions graduated arithmetically, port reference indicia on the frame or holder such that the graduated scale structures may be brought into positions relative to each other and to the holder, to provide a direct reading of desired change in valve setting with respect to valve actuating elements, and indicia means provided on the holder to establish a physical relation between the calculating device and the engine, such as to indicate whether the numerical reading provided by the calculating device represents an increment or decrement in valve stem length or equivalent adjustment in valve mechanism.

5. In a calculating device for use as a physical engine adjunct in steam-engine valve setting, a frame or holder, a graduated structure movably carried by the holder and adapted to be set up to indicate an optimum setting of a slide valve with respect to its valve stem, in one direction of engine operation; a second graduated structure adapted correspondingly to be set up with respect to the holder to indicate an optimum setting of the valve with respect to its stem, in reverse operation of the engine, a graduated element movably associated with the holder and coacting with each of the structures aforesaid, to provide a value from which may be derived by a known factor, a desired change in effective length of eccentric rod, and means for establishing, when the device is in use, a physical relation between the device and the engine, said means coacting with the engine and device to establish said rod change as an increment or a decrement.

6. In a calculating device for use as a physical adjunct to a steam-engine for purposes of valvesetting, a holder, a graduated structure movably carried by the holder and adapted to be set up to indicate an optimum setting of a slide valve with respect to its valve stem, in one direction of engine operation; a second graduated structure adapted correspondingly to be set up With respect to the holder to indicate an optimum setting of the valve with respect to its stem, in reverse operation of the engine, a graduated element movably associated With the holder and coacting with each of the structures aforesaid, to provide a value from which may be derived by a known factor, a desired change in effective length of eccentric rod, and indicia means carried by the holder for dening, when the device is in use, a physical relation of the calculator to the engine such that the readings on the calculator serve to indicate direction of adjustment of the valve with respect to its valve stem, and the nature of change in length 01' the eccentric rod necessary to attain the optimum setting of valve gear.

'7. A calculator of slide rule type for the purpose described, including a longitudinally channeled frame or holder having upstanding and inturned ilanges along its opposite longitudinal margins, a pair of coacting graduated slide elements guidingly e .ged by one of said margins of the ho r. a second channel structure arranged parallel to and carried by the holder between its margins, and coacting with one thereof for guidingly engaging said graduated slide members, and a third graduated slide member carried in the said second channel structure, and movable with respect to the holder in positions contiguous to the slide members irst aforesaid, the hol er and slides being provided with reference pointers through which the slide members cooperate with the holder to provide direct readings of desired changes in valve setting.

8. A calculator device of the type and for the purpose described, including a holder or frame of formed sheet metal characterized by upstanding margins and inturned flanges thereon along the opposite longitudinal margins of the holder, a channel member disposed longitudinally and medially of the holder, a graduated slide element carried by said channel member, a pair of coacting nested graduated scale elements movably and guidedly retained in the holder, by and between one of its flanged margins and said channel member, an additional pair of graduated scale elements movably and guidedly retained between the opposite margin of the holder and the chanel member, the holder and slide elements being provided with reference indicia in addition to their graduations, such that the slide elements of each of said pairs are adapted to cooperate with each other and With the slide element carried by said channel member to provide readings from which may be derived optimum settings of a slide valve with respect to its actuating mechanism, and changes in relation of valve-operating eccentric, to the associated valve gear.

9. A calculating device for use in setting slide valves of steam-engines and as an adjunct to the engine and valve gear, the device including a base or holder, means establishing a useful physical relation of the base to the valve gear, five independently movable, graduated slide elements, together with port markings on the holder, and reference indicators on each of the slide elements, the aforesaid means indicating a physical relation of the device to the engine such that the readings derived from the slide elements will indicate Whether such values are to be applied as increments or decrements in changing the relation of the valve and elements of the valve gear.

lO. A calculating device as set forth in claim 9, characterized in that two of the slide elements are nested, so as to keep them in close physical adjacence, are graduated oppositely to each other, and arranged along one side of a single central slide element graduated in both directions rom a mid-point, and the remaining t\vo slide elements are similarly nested and movably located for cooperative use each with the other and on the opposite side of the said central slide element.

JACK C. HOLDMAN. 

